What is freight class and how to calculate a density based freight class?

Freight classes are defined by the National Motor Freight Traffic Association (NMFTA) and made available through the NMFC or National Motor Freight Classification. The NMFC is a standard that provides a comparison of commodities moving in interstate, intrastate and foreign commerce. It is similar in concept to the groupings or grading systems that serve many other industries. Commodities are grouped into one of 18 classes—from a low of class 50 to a high of class 500—based on an evaluation of four transportation characteristics: density, handling, stowability and liability. Together, these characteristics establish a commodity’s “transportability.”

By analyzing commodities on the basis of the four transportation characteristics and ONLY on the basis of those characteristics, the NMFC provides both carriers and shippers with a standard by which to begin negotiations and greatly simplifies the comparative evaluation of the many thousands of products moving in today’s competitive marketplace.

Here is an example of how to calculate the density based freight class. For example, you have one pallet to ship. The dimensions are 48″x40″x50″. And the gross weight including the pallet is 500 lbs.

First the volume is calculated by multiplying the dimensions together:
48 x 40 x 50 = 96000 cubic inches

Now the volume is converted from cubic inches to cubic feet:
96000 / 1728 = 55.56 cubic feet

To get the density we divide the weight by the volume:
500 / 55.56 = 9 pounds per cubic feet

The density is looked up on the table below. So the class is 100.

Density  NMFC Freight Class
50          50
35          55
30          60
22          65
15          70
13          77.5
12          85
10          92.5
9          100
8          110
7          125
6          150
5          175
4          200
3          250
2          300
1          400
<1          500